Cutting pad



Sept. 23, R OLSON ET CUTTING PAD Filed May 29, 1948 Inventors Arthur ROlson Patented Sept. 23, 1952 UNITED STATES PATENT CUTTING PAD v fArthur R. Olson, Wakefield, Mass., and Edmund W. Gelewitz, Evanston,Ill., assignors to United Shoe Machinery Corporation, Flemington, N. J

a corporation or New Jersey Application May 29,1948,S erialNo.30,106 M a1 Claim, (01. 260-38)- This invention relates to cutting pads and particularly to a cutting pad for a dieing-out machine such as a clickerfor use in cutting leather.

Surfaces against which cutting of sheet material is to be done must besufiiciently hard to support the material being cut so that the cuttingedge will pass through the sheet material to be out without bending thematerial or forcing it appreciably into the surface which is being outagainst. On the other hand, to effect a clean severance of the fibers ofthe material being cut, it is. usually desirable, particularly withcutting dies, that the cutting edge penetrate to a limited extent thesurface being out against. Also, and particularly in cutting surfacesfor use with dieing-out machines'of the character of clickers, thecutting'pad must be able to withstand the severe shock to which it issubjected during the cutting cycle.

Blocks of maple wood, preferably with the grain on end, have beenextensively used to provide a cutting surface for clickers. A seriousshortage of maple wood suitable for this use has developed. Numerousmaterials, such as nylon and cellulose acetate which have hardnesscharacteristics such that they give a satisfactory the surface.

It is a feature of the present invention to provide a clean-cutting andexceptionally wear-re-.

cutting action, have been tried; but although sistant cutting padpossessing the hardness and resistance to breaking under shock fittingit for use in cutting operations.

Applicants have provided a new cutting pad of a material possessing thehardness, strength, and

' dentation; and r I the pressure of the slow recovery of the body ofsuflicient aldehyde to make said resinous product thermosetting. It isimportant that the butadiene acrylonitrile copolymer and the resinousmaterial be present within certain ranges of relation, 1. e.,-is notbrought to the vulcanized state tive proportions in order to give to thecompo sition the novel property of bonding together-at cut surfacesthereof and to provide the pnys ar" characteristics necessaryto give agood. cutting action. g It is to be observed that the cutting pad coinposition, as above described, does not include sulphur. Sulphur isbelieved to react with the residual unsaturatioh of the acryionitrne oohI tent during vulcanization of butadiene-acryiohi trile' copoiymerrubbers. 'l'his BIIe Cl', 1s 'be "f lieved to destroy in some measurethe ab lity of cutting surfaces to bond with each ot er. ,S lhce' thebutadiene-aoryionitrile copolymer in the cut ting pad compositionretains residual unsatura by reaction with sulphur, the present cuttingpad i possesses aremarkab le ability-to heal after c'utr- A filler maybe employed in the cutting pa composition provided the proportion ofnller Ii maintainedbelow the value which would inter fere with theself-bonding properties of the co position. f.

The extraordinary action of the new cuttingn pad in bonding together thesurfaces of fcuts'j formed therein is illustrated in the attacheddrawings, in which Fig. l is a, perspective view of one type ofgcut tingpad according to the present invention";

Fig. 2 is a photomicrograph of a surfaceof th cutting pad in whichsuccessive closely adjacent tions in the-surface of the cutting pad; f 3

Fig. 4 is a phbtomicrographo'fa 'crossfsection' taken on the lines IVIVof F ig. 2 showing thebonding together of the-edg v f a'firstiind e'rtation by the action elf-an dj acent second in- I Fig; 5 is aphotomicrographfshowing the 'bond 1 formed betweenzcut surfaces of 'the'chtting pad composition. '1 I .H; A cutting pad 6 (see.iFig. 1).according. oithe instant invention is a body; having smooth"sur.-.=

faces for cutting, of a composition which mayfu; comprise parts by weigh't of a butadiene-,.-'

acrylonitrile copolymer containing at least 20% of acrylonitrile, andfrom Q80 ;to parts by ;,-5 weight of a synthetic resinous reactionproduct of cashew nutshell oil'and another "phenol v vith sufficientaldehyde to makejthe resinousproduc thermosetting. Optionally" theremay, ,be' 3m cluded up to about 23 parts by volume 'ofa pany of NewJersey, which is understood to have about the same percentage ofacrylonitrile, Other copolymers which may be used are Hycar 0R-15 whichcontains about ibitof acrylonitrile and which is produced by theGoodrich W Company, Chemigum N3 and N4. produced by the lfi r GoodyearTire and Rubber Company of Akron. Ohio, and Butaprenes NXM and NLproduced by the Firestone Tire and Rubber Company of Akron, Ohio. theChemigums and Butaprenes are not known but -are uunderstood to be above20%;. Othe r .eze r loni ri e 99 X Il -1& :,3 a se .i ati ercqn in a sufieieriperc ta of n yils t tiqn .w h..;ih. ..eheueliare ia;... employed.

e P en ic. re n .emplpyed; eraihet e mo: in e q iqnrre u is 9i sa b w nt hel ni e iii s l' ne Lw h... a qehr s- The od Q' i l me ersg pe e 9this. type f resin are fiiisclosed in United states heti o tersl" nt No.2,203 206, granted June 1 1940, A fieea ei e of l ifliird-f, Am gvtheTresinswhich have been found satisfactory for useffiii the pres ntcutting pad composition are the l jura'resin's 12687, 13716 and 1270?which are sg e u te' f ashe ..C .aiQa -p... Inc; North Tonawanda, blewYork.

KfiY-Qfih i efla Wnemlfilhr re d-5.1 compounding ofbutadiene-acrylonitrile copolyme compositions may; be used. Amongthegnosteo sat sfactory 'whichha velbeen tried arethe mate- J h te. a vl ic .eq pr se .-@a i e... gepa ibf ra'fii e swin si w ath r; w asnri'all'prdportion of a stearate soap, the com P05; beifi grqducedbythe T.Van'derb ilt c a black material knownas Spheron f9, an easyprocessing channel black gbtained from afih -it r L- C t, ement I -10 Bean... atts; a d?- mater a k owna sa esman co 3:;- iig l libClpltatedcalcium carbonate of extre e ijl i e particle size andasoap, obtainedfroirftfi Columbia Chemicals Division 9? jihe Pitt sbpsghjlate GlassCompany, I

cfiggegtim a; antioxidant materialssuch as Phefiylibe i efithr amme. a-.n e abl ..i anise ta Ii i us al su p i es e ls aities edseqm t n is mau a tur d..;.. by sseiia tieu t u a r v oce u Av satisgactgrtg methodginvolves. mixing the i resin 60 with the butadiene-acrylonitrile in aBanburyt. mer atgaiiiemperature above the melting. point of thenesimhutrfloelovaaits active curing range. With the Durez resins 12687,13716 and-12707, it has heenufoundi that as'mixing temperature of 5fronzsmmoitoww E i's 'satisfactory for easy mixing; iv! milieu-sinceWhent f bomfihn'e s have been thoroughly mixec fi the niatrfal friaif besheeted out, pressed in g rrifildt afiri subfjecited io heatand pressuresumgi iifit' liffcitiufin .iilressure of at least qi i3' ,fli i,iqsj.iif fi b i it has at a m r turiijf abputgifim gand l lji jlime ofatleast. d t ttain ais li siae ee e .have.rs

The exact acrylonitrile contents-of .on having va specific gravity of2,75 andf I 0 maintainedat irom.1:;;to 20031. ;When th been foundsatisfactory. The preferred curing time is about 25 minutes.

In addition to the above-referred-to property of bonding of cut surfacesof the material, a cutting pad according to the present invention shouldhave the following physical characteristics, as determined by ASTMtests, in order to function most-effectively as a cutting padefor a cicker:

Hardness-Shore D -80.

Tensile strength At least 2500 pounds per square inch. E1o ngation- 5%to 50%.v Shearstrength At least 800 poundsper square inch. Impactstrength (Izod At least 3 foot pounds.

.unnotched). Rockwellv M" hard- -30 to 30.

ness;

Cutting padv compositions. within, thelabove-t identified rangesofrelative proportions and.pos;-,,. sessing the above-listed .physicalproperties give extremely'long wear and great resistance. to deterioration. Compositions containing a pro'por-Qv 4 tion ofphenolicresin below the .,ranges, given. above resultin a surfaceonwhich cutting. willbe uneven or rag ed, whilev compositions containing agreater percent'ageof phenolicresingiveasur face which will deterioraterapidly through chi ping or crumbling during cutting. The percent:v ageof filler is not as important as thepereentage, up of resinous materialand satisfactory. cutting. blocks have been made.containing ,nofillnand,ppntaining as high as 23 parts by .volumejofthej. filler to 100 parts byvolume of butadiene;acryloj... nitrile copolymer ,rubber.. ,Incompounding obtain the most satisfactory cutting .surface it has beenfound that as the percentage of .filleris increased, the proportion ofphenolic resin to the butadiene-acrylonitrile copolymer should. be de.creased to avoid brittleness. However, within the ranges offilleroontent given, highly, satisfactory cutting surfaces may beobtained... '1

Notwithstanding the advantage. obtained. in compositions containing nosulphur, cutting .pads. vi so e ha re uc dse f-healin pr perties. usefulfor somepurposes have beenQprepared containing as high as 5partsofsulphurwithlflflg. 1 parts of butadiene-acrylonitrile .copolymer.

1 The following examples 'are given to. aidrincr.understandingtheinventionand it is to be under: stoodthat the inventionis n0t ,m ted, .to the,.-;;. sp ifi p po t nsror hieredientsaemplcyiedtmthe. exam les-1. C a

Example g Onei-hundred parts. by .weight. ofarbutadieneacrylonitrile-copolymer'rubber' containing 33% otacrylonitrile (Hycar. OR'25.) Wasxcombinedwith parts by weight of.a-synthetic-resinous'reac tion product of cashew nutshell oilandanother-: phenol, with sufiicient aldehyde....(8%; by weight-of theresin of hexamethylaminetetramine)wtomake: saidresinousproductthermosetting, 15 parts by Tax. weight (8.6 parts by volume toparts ibyvols ume of the copolymerrubberizof channe1- -b1ack 1. (Spheron#9) and one partby Weightoiphenylez beta naphthylamine;;. (Neozone)';were smixedsin' a Banbury' mixerof which the temperaturewa mixing hadbeen -.com pl ete.d.a the material was;

and. sh d; 1 n 0slbssh essure pensquares 3 411 25 m utes: t tsneratumzof abou The resulting cutting pad had a hardness (Shore D) of66, a tensile strength of 3390 pounds per square inch, an elongation of45%, a shear strength of 960 pounds per square inch, an impact strengthof 3.7 foot pounds and a Rockwell M hardness of +19.

The cutting pad thus obtained gave an excellent cutting action in aclicker and was still functioning satisfactorily after seven months ofnormal use as a, cutting pad for a clicker in cutting room operation.

The following tests were carried out on a section of a cutting pad 6 ofthe above composition: A punch apparatus (see Fig. 3) comprising a guidesleeve and a, cylinder 12 slidably mounted in the sleeve [0 and havingin the center of one end face It a penetrating cone I3 having a base of.125 inch and a height of .125 inch was placed on a surface 8 of thecutting pad with the point of the cone resting on the surface of thepad. The cone was driven into the pad to its full extent by a sharp blowwith a hammer on the upper face l8 of the cylinder l2. The cylinder andcone were lifted from the sleeve, the sleeve moved 3 the cylinderreinserted in the sleeve and the cone driven into the cutting pad asecond time.

As shown in Fig. 2, which is a photomicrograph at 15.4 diameters withdiffuse, nondirectional fluorescent lighting, and in Fig. 4, which is aphotomicrograph at 15.0 diameters taken with oblique lighting using anincandescent lamp, of a cross section on line IVIV of Fig. 2, throughthe indentations in the cutting pad, the first indentation 20 has beensubstantially filled by material displaced in making the secondindentation 22 and the displaced material has bonded uniformly withother portions of the material so that there is no visible joint or lineof separation where the surfaces of the first indentation 20 werebrought together by displacement of material in making the secondindentation 22.

To further show the bonding characteristic possessed by the cutting padcomposition, two freshly cut surfaces 24 and 26 of the cutting padcomposition were brought together and pressed together under 2000 poundsper square inch for a period of 2 hours. The surfaces were found to haveadhered tightly together. When the surfaces were wedged slightly apartby the insertion of a knife edge (see Fig. 5 which is a photomicrographtaken at 66 diameters with oblique incandescent lighting) legs 2-8, thatis, filaments or threads of the composition, extended from one cutsurface to the other cut surface clearly demonstrating that a firm bondhad been formed between the surfaces.

Example II 40 parts by weight of a butadiene-acrylonitrile copolymerrubber (Hycar (DR-25) was combined with 47 parts by weight of asynthetic resinous reaction product, cashew nutshell oil and anotherphenol together with sufficient aldehyde (8% by weight of the resin of,hexamethylaminetetramine) to make said resinous product thermosetting, 2parts by weight of zinc oxide, 4 parts by weight of sulphur, 0.8 part byweight of stearic acid, 0.8 part by-weight of Altax (benzothiazyldisulfide), 3.8 parts by weight of dibutyl sebacate, and 1.7 parts byweight of a channel black were mixed in a Banbury at a temperaturerising from an initial temperature of F. to a final temperature of 150F. The mixture was sheeted out, dusted with talc and disposed in a mold18"x36"x1". The mixture was cured for 30 minutes at a temperature ofabout 310 F. under a pressure of 1000 pounds per square inch. The moldedpad was removed. The pad had a Shore-D hardness of 68, a tensilestrength of 3530 pounds per square inch, an elongation of r 25%, a shearstrength of 1130 pounds per square inch, a notched Izod impact strengthof 3.2 foot pounds, and a Rockwell M hardness of 18. The cutting padthus obtained gives a quite satisfactory cutting action in a clicker.

Having thus described our invention, what we claim as new and desire tosecure by Letters Pat ent of the United States is:

A clean cutting, wear resistant cutting pad comprising a smooth surfacedbody of material of which cutting surfaces will bond when pressedtogether, said material comprising the product of molding undersufficient heat and pressure to effect curing a mixture of 100 parts byweight of a rubbery butadiene-acrylonitrile copolymer containing atleast 20% acrylonitrile, about parts by weight of a synthetic resinousreaction product of cashew nutshell oil and another phenol, sufficientaldehyde to make said resinous product thermosetting and channel blackin the proportion of 8.6 parts by volume to parts by volume of thebutadiene-acrylonitrile copolymer, said cutting pad having a Shore-Dhardness of 60 to 80, a tensile strength of at least 2500 pounds persquare inch, an elongation of from 5% to 50%, a shear strength of atleast 800 pounds per square inch, a notched Izod impact strength of atleast three foot pounds and a Rockwell Mf hardness of from -30 to 30.

ARTHUR R. OLSON. EDMUND W. GELEWITZ.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,203,206 Shepard et a1 June 4,1940 2,281,877 Green May 5, 1942 2,325,620 Maeser Aug. 3, 1943 2,532,374Shepard Dec. 5, 1950.

OTHER REFERENCES Shepard et al., Modern Plastics, October 1946, pages154-156, 210 and 212.

Searer, Rubber Age, November 1947, pages 191-193.

Newberg et al., Rubber Age, February 1948, pages 533-539.

